As equipment is entered into the software, the reactance and resistance, or total impedance, is calculated for each equipment type. When a full electrical system is modeled in EasyPower®, each branch of the system where a fault may occur can be broken down into its equivalent Thevenin impedance based upon each piece of equipment in that branch of the system. These values are then used to show current flow characteristics in a faulted situation.

Over-Dutied Equipment Analysis

Protective devices (fuses & breakers) perform the essential function of interrupting current and thereby limiting the release of energy that occurs during an arc flash. It is the scope of equipment duty to verify these protective devices have sufficient interrupting capability. Equipment duty calculates available short-circuit current against manufacturer ratings and expresses this ratio as a percentage.

Any protective device with insufficient capability to interrupt a three-phase short-circuit will be highlighted in red and flagged as a violation. A piece of equipment trying to clear a fault that is larger than the interrupting duty could fail to open and clear the fault. Over-dutied equipment is a hazard beyond an arc flash incident. If a fault were to occur at the load side terminals of an over-dutied breaker, the breaker would likely come apart in the form of an explosion sending breaker pieces out as shrapnel. When these items are found, they will be recommended for replacement.